Electron tube



Patented Mar. 8, 1938 UNITED STATES PATENT FFICE ELECTRON TUBE Germany Application August 4, In Germany 3 Claims.

The invention is concerned with an arrangement which serves to act on the path or trajectory of pencils consisting of electrons or ions. This arrangement according to the invention corn 5 sists in that the electrodes are disposed in such a proximity to the path and are charged up to such potentials that the curves of the paths are influenced only in one plane, while in the plane at right angles thereto they are rectilinear in form.

An exemplified embodiment of the invention adapted to act upon the path of electron rays shall be described in more detail in what follows by reference to the drawing wherein Figures 1a, 1b and 2 illustrate forms of the present invention.

Referring to the drawing, Hi denotes a tube of a vacuum vessel lined or coated with a metal layer in which are confined two plates 1 l and if being of equal length and parallel to the tube axis, and being equally long in the direction of the tube axis. The supposition is that these two plates are at a negative potential in reference to the tube wall l0.

Inside the vacuum vessel is also situated a conventional electron gun structure as shown schematically at 8, which includes a source of electrons 9 for producing the electrons which are directed along a path between the plates i and I2.

The fact that in this disposition there occurs an action only upon the curves of the paths in one plane, while in the plane at right angles thereto the path curves do not undergo any change in direction, shall be explained for those rays which travel in planes at right angles to each other and which pass through the axis of the tube 35 l 0. The rays traveling in the plane A-A, Fig. 11),

shall be indicated by the marginal rays l3, l4.

They traverse as they enter and leave the equi potential surfaces indicated in Figure by dotted lines whereby curving of the path is produced. 40 The curvature occurs upon entrance into the plates l I, l 2 in the same sense as on leaving them so that the convergence of the rays I3 and Hi traveling in the plane AA is increased. The cathode rays leave the plates H, l2, as will be seen, inside the solid angle which is bounded by the marginal rays l3 and M. The arrangement thus described may be termed an electrical cylindrical lens from its analogue in optics.

In the plane being at right angles to the former and which in Fig. 1a is indicated by 3-38, no deflection of the cathode rays takes place at all, for the equipotential surfaces are traversed by the cathode rays traveling in the plane B-B exactly at right angles.

If the plate arrangement shown in Fig. 1 is used twice, with the two plate pairs Ha, 12a, and l lb, l2b, being mounted at right angles to each other, with two corresponding or cooperating plates 1934, Serial No. 738,432 August 2, 1933 being at the same potential as shown in Fig. 2, it is possible to produce a pencil of electron rays of rectangular cross-sectional shape.

In using the construction as shown in Figure 2, one pair of plates, for instance Ha, Ha, cause the beam of electrons to be focused or converged in one plane which in themselves would produce at the point of focus a beam of electrons rectangular in cross-section with a length materially in excess of the width. The other pair of surfaces, lib, I212, cause the beam of electrons to be converged in another plane perpendicular to the plane of convergence caused by the first pair of plates, with the result that the cross-section of the beam of electrons at the point of focus is then a very small rectangular area.

The invention is similarly applicable to influencing the path of ionic ray pencils.

Having thus described the invention, what I claim is:

1. In an electron tube, means to develop an electron beam including a cylindrical potential surface, means to position the said surface coaxial with respect to the developed beam, a first and a second pair of opposed plane surfaces, means for supporting said pairs of surfaces so that the developed beam passes therebetween with the plane of said first pair of surfaces normal to the plane of said second pair of surfaces, said surfaces being adapted to be maintained at substantially the same potential and at a potential negative with respect to the potential of said potential surface whereby the electron beam will be converged and focused into a small and substantially square area.

2. In an electron tube, means to develop an electron beam including a cylindrical potential surface, means to position the said surface coaxial with respect to the developed beam, 2. first and a second pair of opposed plane surfaces, means for supporting said pairs of surfaces so that the developed beam passes therebetween with the plane of said first pair of surfaces normal to the plane of said second pair of surfaces, said surfaces being adapted to be maintained at substantially the same potential and at a potential negative with respect to the potential of said potential surface whereby each pair of surfaces will produce a cylindrical electron lens.

3. The method of operating electron beam tubes which comprises the steps of releasing a stream of electrons from a source, directing the released electrons in the form of a beam toward an impact area, and electrically compressing the beam in perpendicular directions to produce perpendicular cylindrical lens effects.

MAX KNOLL. 

